Four persons, three Central Reserve Police Force personnel including an assistant commandant and a suspected Maoist were killed in an encounter in Bihar's east Champaran district on Wednesday night.

The six-hour long gunbattle occurred when a joint team of the state police and the CRPF conducted a raid following a tip-off that an armed squad of Communist Party of India-Maoist was present at Lakhminia village in adjoining Sheohar district, Inpector General (Operations) S K Bharadwaj told PTI.

The Maoist rebels, who escaped to Kadma village from Lakhminia, fired at the security personnel killing an assistant commandant and two constables of CRPF. A Naxalite was also killed in the exchange of fire.

"The gunfire has stopped now and we suspect many more casualties among the Naxalites whose bodies may be found after dawn," the IG said.

Bharadwaj said the district magistrate and superintendent of police of east Champaran, besides the commandant of the CRPF battalion posted in the area were camping at the spot.

The encounter comes barely a day after the Maoist rebels clashed with wardens and inmates at the Beur central jail in Patna following the suicidal death of their comrade Nagina Manjhi at the prison hospital on December 14.